JP-Y2-62-4006 describes a conventional air-conditioner for a vehicle, and a seat heater which is automatically controlled according to an opening of an air mix door or a target blow-off temperature. Moreover, it is well-known that energy is required to be saved in air-conditioning by setting an eco-mode.
In the case where the seat heater is controlled according to the opening of the air mix door or the target blow-off temperature, the seat heater may be activated only when a temperature in the passenger compartment is low. An occupant in a passenger compartment may feel cold when the seat heater is not activated. Especially at the eco-mode time, an occupant is more likely to feel cold, because the air-conditioning level (degree) is lowered in the eco-mode time to save energy.
The seat heater of JP-Y2-62-4006 is embedded in a seat of the vehicle. Electric power supplied to the seat heater is controlled by a controller. Specifically, the electric power supplied to the seat heater is increased, as the opening of the air mix door is increased, or as the target blow-off temperature is raised.
The heat generating amount of the seat heater is automatically controlled according to the load of the air-conditioning such as the opening of the air mix door or the target blow-off temperature. When the load is large (for example, at a very cold time), the heat generating amount of the seat heater is increased to accelerate the warm-up effect of the seat heater. On the other hand, when the load is small, the heat generating amount of the seat heater is reduced to avoid wasteful energy consumption.
However, if outside air temperature is very low at the very cold time, the opening of the air mix door or the target blow-off temperature is set into a large (high) value. If the large value is maintained for a long time, the heat generating amount of the seat heater is also maintained as large even after the temperature in the passenger compartment becomes stable. In this case, an occupant in the passenger compartment feels too hot due to the too much heat of the seat heater. Similarly, if the outside air temperature is very high at a very hot time such as summer, the occupant may feel too cold.